The Mopey, Modern Priest
In many ways, "Four Quartets" is different from Eliot's other poems; it's tone, for starters, allows for much more hopefulness than poems like "The Waste Land" or "The Hollow Men." But one thing that remains pretty consistent is Eliot's obsession with diagnosing the spiritual emptiness of modern life and trying to figure out its causes.
What's particularly Eliot-ish about "Four Quartets" is how openly religious the thing is. Case in point: "That we are sound, substantial flesh and blood— / Again, in spite of that, we call this Friday good" (350-351). Now it's not easy to say exactly what religion it's endorsing, but it's important to note that Eliot wrote about this stuff during a time when many great authors and poets weren't all that enthusiastic about religion. George Orwell, for one, criticized this poem a lot, saying that it was a sad departure from Eliot earlier (and apparently better poetry). The reason for this is that Orwell believed that Eliot "does not really feel his faith, but merely assents to it for complex reasons. It does not in itself give him any fresh literary impulse."
Basically, Orwell's beef seems to be with the fact that Eliot is looking to religion for poetic inspiration when (Orwell believes) religion doesn't really have any good poetry left in it. If you check out Orwell's article, you see that he has some really solid arguments for why he feels this way. But at the same time, you can't really read the dreary "The Waste Land" and be all that surprised at the angle Eliot later takes up in "Four Quartets." The dude wants spiritual fulfillment in the modern world, and he wants his readers to have the same thing.